Abstract

Arunachal Pradesh is one of India’s biodiversity hotspots. The present study was based on samples collected from Tirap district in Arunachal Pradesh. This district is located at latitude 26°-38’N and 27°-47’N, longitude 96°-16’E and 95°-40’E, altitude 1200-1300 masl. The terrain is marked by high hills, deep ravines and valleys through which streams and rivers flow. The entire district consists mainly of tropical and subtropical evergreen forests with rich and varied fauna. Twenty soil samples were collected at random from natural forest areas. A total of 85 genera of nematodes were recorded, with predators representing the highest number (32%), followed by bacterial feeders (20%), fungal feeders (22%), herbivores (15%) and omnivores (11%). In terms of individual abundance, the fungal feeders were the most dominant group (29%), followed by predators (25%), bacterial feeders (20%), herbivores (16%) and omnivores (10%). A minimum of eleven and a maximum of 26 genera per sample were recorded with most of the samples containing fifteen-twenty genera. In terms of individual abundance, 600-1040 specimens per 100 cm3 of soil were recorded with most of the samples containing 600-800 individuals. There was high positive correlation between omnivores and bacterivores, and moderate positive correlation between omnivores and herbivores, and omnivores and predators. Some positive correlation also existed between omnivores and herbivores, and predators and bacterivores. Three-dimensional diagrams based on cp values show that genus-based diversity was higher among cp 3-5 groups than cp 1 and 2 groups. Dendrograms of cluster analysis of different indices indicated a close functional similarity in the samples of this region, except for a few samples where the enrichment index was zero or very low because bacterial feeders (Rhabditidae and Panagrolaimidae) with cp 1 were absent or few in number.